In hydraulic systems in which the use of flexible tubes or hoses is disadvantageous or impossible, e.g. as a result of a high internal pressure in the pipe system, it is known to provide a flexible connection between rigid pipe sections by means of a coupling device comprising a spherical member connected with one pipe section and supported in a spherical bearing in a housing connected with the other pipe section, the spherical member further comprising a duct forming a connection between the pipe sections. In order to maintain the movability of the coupling device, the high pressure pipe section is connected through the duct in the spherical member with chambers on opposite sides of the spherical member having a form so as to equalize the pressures on both sides of the spherical member.